Clamp-spreading mechanism for buttonhole-sewing machines



April 6 1926. r E. B. ALLEN vcum? SPREADING MECHANISM FOR BUTTONHOLE sswme MACHINES T Filed April 11. 1924" ATTORNEY Patented an, e, 192s.

* UNITED stares rarest amen EDWARD B. ALLE1\T, '0F nnwrown, CONNECTICUT, Assrenon TO THE sIneER MANU- FACTURING COMPANY, OF ELIZABETH, NEW JERSEY, A CORPORATION' OF NEMf JERSEY.

CLAMP-SPREADING MECHANISM FOR BUTTONHOIiE-SEWING MACHINES.'

Application filed April 11, 1924. Serial No. 705,817,

To all whom it may concern: I

Be it known that I, Enwnnn B. ALLEN, a citizen of the United States, residing at Newtown, in the county of Fairfield and State of Connecticut, have invented certain new and useful Improvements in Clamp Spreading Mechanisms for Buttonhole Sewing Machines, of which the following is a specification, reference being had therein to the accompanying drawings.

'The present invention has for an object to provide a 'huttonhole sewing machine with an automatic clampspreading mechanism designed to impart simultaneous and equal spreading movements to the clampsections vand having a single manually operable element and connections for regulating the extent of the equal spreading movements imparted to the work-clamp sectlons.

A further object of the invention is'toprovide for the desired regulation while maintamlng constant the respective spread positions of the work-clamp sections, a so that the area of, material exposed between the upper clamping feet to the action of the sewing mechanism will remain constant regardless of the amount of spreading movement imparted to the clamp-sections.

Tothe attainment of the ends in view, use has preferably been made of the clamp spreading toggle mechanism disclosed, for example, in my Patent No. 1,372,472,.re

issued April 4, 1922, under No'. 15,32t.

One of the lateral clamp-engaging slideblocks of said toggle inechanismus, for

the purpose of the present disclosure, EX- tended at its outer end and fitted with a pivoted cam-disk having an eccentric operative edge and a regulating handle which may be :readily grasped by the operator. The supporting plate for the toggle mechanismhas secured thereto a stop-element so positioned as to be encountered by the operative edge of the cam-disk and thus, through the toggle mechanism, limit or determine the unspread positions of both clamp-sections.

vBy shifting a single regulating'handle, the operator may, at will, vary the amount 'disclosed in my said reissued patent; the

of spread of the work-clamp sections while maintaining constant the respective spread positions of said sections and insuring at all times that the work will be subjected to equal spreading actions at the opposite sides of the longitudinal center line through the buttonhole-slit, an important consideration particularly in machines which cut the buttonholebeforesewing-it. Y

lnthe accompanying; drawings, Fig, 1

is a horizontal section through the bracket- I arm standard of a sewing machine'embodying the invention, showing the work-clamp in plan. Fig. 2 is a bottom, plan view of a fragment of the clamp-spread1ng-toggle supporting plate of the work-clamp'inechanism. Fig. 3 is a section through the clamp-spread]ng-toggle supporting plate transversely of the machine bed and Fig.

4: is a plan view of the left lateralslideblock showing its; end extension. The machine comprises the usual frame -1nc'ludmg the bed 1 upon whlch 1s mounted the usual longitudinal sl'i'de-frame2 carry,- ing the cross slide plate 3 to which is pivot,- ally connected at 4, 1 the separable worl clamp sections 5, 5 including the usual worksupporting plates 6, 6, and upper clamping feet'7, 7. The clamp sections 5, 5 are normally urged to their respective unspread positions by means of the usual springs 8,

The clamp-spreading mechanismis in the form of a toggle designed to impart equal spreading movements to] the respective clamp-sections It comprises the lateral slide-blocks Q, 9 carrying the abutment screws 10, 10 against which rest the heads of the screws 11, 11 mounted onthe respective clamps-sections 5. v y 7 The slide blocks 9 are fcon ected, respee tively, to the opposite ends of the lever12 by means of the links 13,14, thelatt'erhaving anext'ension lo adapted 'to be struck by forward movement of the clamp-um spreading arm shown in section at 16. The pivotal connection or pin 17 betweenthe ever 12 and link 18 is embracediby the forked inner end of the toggle straighten-' I ing lever 18 the outer end of. which is given a forward push the element 19 mounted on a third or downwardly extending arm of the clamp-closing lever 20. EX-

usual from the continuously rotating power means or pulley 20.

cept as hereinafter describedfth'e,construci,

V The left-hand lateral slide-block 9 is formed with an upwardly offset end extension 21 terminating in a circular head 22 to the under face of which is pivoted at 23 the regulating stop .24 in the form of a camdisk having an active eccentric edge-opertion, between the points 25, 26, Fig. 2, which strikes the outer end of the stop-arm 27 adjustab ly fixed to the toggle supporting plate by the screw and slot connections 28. The cam-disk 24- is formed with a regulating handle 29 which is readily accessible to the operator. The disk 24 also carries a pin 30 located in the recessed quadrant 31 of the head 22; the latter bearing indicating marks in connection with which the pin serves as a pointer to indicate the amount of spreading movement imparted to the clampsections. The cam-disk 24 strikes the stop 27 when the toggle 12, 13, 1% is broken and limits or determines the unspreadpositions of the respective clamp-sections. A shift of the regulator 29 affects both clamp-sections equally so that the spreading or unspreading actions are always equal at the opposite sides of the longitudinal center line of the buttonhole. Moreover, the spread positions of the clamp-sections are not affected by a shift of the regulator 29 and the area'of work exposed to the sewing mechanism is always the same, thus affording a desired uniformity of sewing relations between the sewing mechanism and the work-clamp, regardless of the amount of spread imparted to the clamp-sections.

Having thus set forth the nature of the invention, what I claim herein is 1. In a buttonhole sewing machine, the

combination with the machine bed, of a work-clamp having separable sections, continuously rotating power means, automatic clamp-spreading mechanism actuated by said power means andv including means interconnecting the clamp-sections for simultaneously 'spreading'the latter, spring means for returning said sections to their unspread positions, and amanually adjustable regulator in the form of a stop disposed at the side of the machine bed and cooperatively related to said interconnecting means to limit the return movement of said sections under the influence of said spring means.

2. In a buttonhole sewing machine, the combination with the machine bed, of a tinuously rotating power means, automatic,

clampspreading mechanism actuated by said power means and including means inter connecting the clamp-sections for simultaneously spreading the latter, spring means for returning said sections to their unspread positions, and a manually adjustable regulating lever disposed at the side of the machine bed and having an eccentric stop.- portion cooperatively related to said interconnecting means to limit the return movement of said sections under the influence of ously spreading said sections, and a manu ally operable regulating stop for varying the limit to which the toggle mechanism may be moved to unspread the clamp-sections,

4. In a buttonhole sewing machine, a work-clamp having separable sections, a slide-block support, laterally separable slideblocks carried by said support and engaged by said sections, a toggle-mechanism for shifting sald slide-blocks simultaneously inopposite directions, a stopelementcarried by one of said slide-blocks, and a coacting stop-elementcarried by said slide-block support, one of said stop-elements being manu, ally operable to regulate the range of action of the toggle mechanism;

5. In a buttonhole sewing machine, a work-clamp having separable sections, laterally separable slide-blocks engaged by said sections, one of said slide-blocks having an end-extension, a toggle mechanism for shift regulating the amount of spreading movement imparted to said sections by said toggle-mechanism,

In testimony whereof, I have signed my name to this specification.

EDWARD B. ALLEN.

I i I)? 

